Pseudomonas syringae pv. syringae, which causes bacterial canker, is the most polyphagous bacterium in the P. syringae complex because of its broad host range. This pathogen is considered the major bacterial disease in cherry orchards. In this study, several samples were collected from infected sweet cherry (Prunus avium L.) trees in different locations of the Marmara region in Turkey between 2016 and 2018. Sixty-three isolates were identified as P. syringae pv. syringae by pathogenicity, LOPAT, GATTa, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry tests. Total genomic DNA was extracted to confirm identity, followed by PCR amplification of syrB and cfl genes. Out of 63 isolates, 12 were randomly selected for repetitive element sequence-based PCR and multilocus sequence typing analyses to gain insight into the relationships of those isolates. The cluster analysis of enterobacterial repetitive intergenic consensus-, repetitive extragenic palindromic-, and BOX-A1R-based repetitive extragenic-palindromic-PCR techniques could classify the isolates into two distinct clusters. Phylogenetic analysis was carried out to obtain the relation between isolates and the location. The multilocus sequencing typing analysis of gyrB, rpoDp, rpoDs, and gltA genes allowed a clear allocation of the isolates into two separate main clusters. The relationships among the isolates were also evaluated by constructing a genealogical median-joining network (MJN). The isolates from six locations produced 11 haplotypes that were illustrated in the MJN. The results of this study proved that location could not be an indicator for showing the genetic diversity of P. syringae pv. syringae from cherry orchards. As the genetic variability of Pseudomonads has been demonstrated, this study also showed high diversity among different isolates even within the populations. While more research is recommended, the results of this study contributed to a better understanding of the evolutionary progress of P. syringae pv. syringae and the genetic diversity of sweet cherry isolates.
Keywords: Prunus avium; bacterial canker; multilocus sequence typing; phylogenetic analysis; repetitive element sequence-based PCR.